Inflatable balloon catheter with purge mechanism and method

ABSTRACT

An improved balloon catheter which includes a purge mechanism for purging air from the catheter prior to use. The purge mechanism is sized to allow air to pass through, but highly restricts the flow of liquids. Air remaining in the catheter after purging is allowed to diffuse through the balloon prior to use. The mechanism is especially useful with low-pressure, gas-permeable, compliant balloons.

CROSS-REFERENCE TO A RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 09/487,128, filed Jan. 19, 2000, and isincorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to vascular balloon catheters which may beused for percutaneous transluminal angioplasty procedures, oralternatively may be used to position and expand a reinforcing stentwithin a blood vessel. In particular, this invention is especiallyadapted to treatment of small diameter blood vessels within the brainand may, for example, be used to temporarily occlude a blood vessel toevaluate the results of the occlusion prior to placing a permanentocclusion device within the vessel.

[0004] 2. Description of the Prior Art

[0005] Medical catheters exist for a wide variety of purposes, includingdiagnostic procedures and interventional therapy, such as drug delivery,drainage, and perfusion. Catheters for each of these purposes may beintroduced to numerous target sites within a patient's body by guidingthe catheter through the vascular system. A wide variety of specificcatheter designs have been proposed for such different uses.

[0006] Of particular interest to the present invention, small diametertubular access catheters are presently being used for diagnostic andinterventional therapy techniques for vessels within the brain, such asthe imaging and treatment of aneurysms, tumors, arteriovenousmalformations, and fistulas. Such techniques place a number ofrequirements on the catheters that are to be employed. The primaryrequirement is size. The blood vessels in the brain are frequently assmall as several millimeters, or less, requiring that catheters have anoutside diameter as small as one French (0.33 millimeters). In additionto small size, the brain vasculature is highly tortuous, requiring thatcatheters used in vessels of the brain be very flexible, particularly attheir distal ends, to pass through the regions of tortuosity.Additionally, the blood vessels of the brain are relatively fragile, soit is desirable that the catheters have a soft, non-traumatic exteriorto prevent injury.

[0007] In the case of balloon catheters, prior to introducing thecatheter into a human body, it is desirable to purge air from thecatheter with a liquid to prevent the air from being introduced intoblood vessels. In the past, purging the catheter involved inflating theballoon section of the catheter to allow the air to escape out of thedistal end of the balloon and then providing some mechanism to preventair from reentering the balloon while it is being deflated.

[0008] U.S. Pat. No. 5,728,065 to Follmer, et al., discloses a ballooncatheter with a vent hole disposed near the distal end of the balloon.The vent hole normally lays against the surface of an inner tubularmember, preventing gases from entering the balloon. During purging, theballoon is inflated, the distal end of the balloon opens exposing thevent hole, and gases and a portion of the inflation medium flow out.

[0009] U.S. Pat. No. 4,811,737 to Rydell, discloses a balloon catheterwith a slit in the distal portion of the tubular member. Fluid isinjected into the catheter and flows through multiple inflation ports toexpand the balloon. The purging fluid forces the air within the balloonthrough the slit in the tubular member.

SUMMARY OF THE INVENTION

[0010] In accordance with the present invention, there is a ballooncatheter having a catheter body and an inflatable balloon. The catheterbody comprises at least one tubular member having a tubular wall, aproximal end, a distal end, and having a lumen extending throughout thelength of the tubular member. The inflatable balloon has a main bodyportion, a proximal portion, and a distal portion. The proximal portionand distal portion extend from the main body portion. The distal portionof the balloon is bonded to the tubular member near the distal end ofthe tubular member and the proximal portion of the balloon is bonded tothe tubular member proximal to the distal portion of the balloon. Theinflatable balloon is formed from a gas-permeable material. The ballooncatheter also includes a coupling member mounted on the proximal end ofthe tubular member with the lumen of the coupling member in fluidcommunication with the lumen of the tubular member. A syringe or otherhydraulic pressure device is coupled to the coupling member to apply aliquid within the lumen of the tubular member. In order to purge thesystem of air, at least one aperture extends radially through the wallof the tubular member at a point proximal to the proximal portion of theinflatable balloon.

[0011] In accordance with another aspect of the invention, there is aballoon catheter having a catheter body and an inflatable balloon. Thecatheter body includes an outer tubular member having a tubular wall, aproximal end, a distal end, and having a lumen extending throughout thelength of the outer tubular member. The catheter body further includesan inner tubular member having a proximal end, a distal end, and a lumenextending therethrough. The inner tubular member is disposed coaxiallythrough said lumen of the outer tubular member. The inflatable balloonhas a main body portion and proximal and distal portions which extendfrom the main body portion. The proximal portion of the balloon isbonded to the distal end of the outer tubular member and the distalportion of the balloon is bonded to the distal end of the inner tubularmember. The inflatable balloon is formed from a gas-permeable material.The balloon catheter also includes a coupling member mounted on theproximal end of the tubular member with the lumen of the coupling memberin fluid communication with the lumen of the tubular member. A syringeor other hydraulic pressure device is coupled to the coupling member toapply a liquid within the lumen of the tubular member. In order to purgethe system of air, at least one aperture extends radially through thewall of the tubular member at a point proximal to the proximal portionof the inflatable balloon.

[0012] In accordance with other aspects of the invention, the apertureis circular and has a diameter between approximately 0.0005 inches and0.0014 inches, preferably about 0.0010 inches.

[0013] In accordance with another aspect of the invention, the liquidapplied within the lumen of the tubular member exerts a fluid pressurebetween about 20 psi and 45 psi and thereby causes air to pass throughthe aperture.

[0014] In accordance with another aspect of the invention, theinflatable balloon is placed within a protective tube therebyrestricting the ability of the balloon to inflate.

[0015] In accordance with another aspect of the invention, there is amethod of purging air from a balloon catheter which includes the stepsof: First, placing the inflatable balloon within a protective tube torestrict the inflation of the balloon. Second, injecting liquid into thelumen of the tubular member thereby forcing air to be evacuated from theballoon catheter through the purge aperture. Third, removing theprotective tube. Fourth, inflating the balloon. Fifth, allowing any airremaining within the balloon to diffuse through the inflated balloon.And, finally, submerging the balloon in liquid while deflating theballoon to prevent air from reentering the catheter body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a partially sectioned view illustrating a ballooncatheter made in accordance with the invention;

[0017]FIG. 2 is a sectioned view of the catheter body near the proximalportion of the balloon;

[0018]FIG. 3 is a sectioned view of the catheter body near the distalportion of the balloon;

[0019]FIGS. 4 through 7 illustrate a sequence for purging the catheterwherein:

[0020]FIG. 4 shows the distal end of the catheter inside the protectivetube;

[0021]FIG. 5 shows the balloon inflated within the protective tube;

[0022]FIG. 6 shows the balloon mostly deflated with the protective tuberemoved; and, FIG. 7 shows the balloon normally inflated.

DESCRIPTION OF A PREFERRED EMBODIMENT

[0023]FIG. 1 illustrates a partial section view of a balloon cathetermade in accordance with the present invention. The balloon catheter 2includes an outer tubular member 4, having a proximal end 6 and a distalend 8, and an inner tubular member 10, having a proximal end 12 and adistal end 14. A dual port Y-connector 16 is coupled to the proximal end6 of the outer tubular member 4 and the proximal end 12 of the innertubular member 10. An inflatable balloon 18, having a main body portion20, a proximal portion 22, and a distal portion 24, is secured to thedistal end 8 of the outer tubular member 4 at the proximal portion 22 ofthe inflatable balloon 18. The distal portion 24 of the inflatableballoon 18 is, in turn, secured to the distal end 14 of the innertubular member 10. With the balloon catheter of the present invention,fluid may be applied through a lumen in a side port 26 of theY-connector 16.which communicates with the passageway between the innertubular member 10 and the outer tubular member 4 to thereby inflate theballoon 18. Preferably, the fluid is applied using a syringe (not shown)coupled to the side port 26 of the Y-connector 16, although other meansknown to the art may be employed as well. In order to steer the catheterthrough the vasculature, a guidewire is typically passed through aproximal port 28 of the Y-connector 16 and through the lumen of theinner tubular member 10 which serves to assist in steering the distaltip of the catheter through the vasculature.

[0024] As illustrated, the outer tubular member 4 includes a proximalportion 30 and a distal portion 32 of differing diameters, with theproximal portion being larger than the distal portion. In addition, theproximal portion 30 is formed from nylon having a durometer of 75D andthe distal portion 32 is formed of polyurethane having a durometer of65D. The reduced diameter of the distal portion 32 of the outer tubularmember 4, together with the decrease in durometer, results in the distalsection of the catheter being more flexible and therefore may be moreeasily passed through the tortuous vessels of the human body.

[0025] The inner tubular member 10 is comprised of a thin inner layer34, a reinforcing layer 36 placed on top of the inner layer 34 and asoft outer layer 38 which surrounds and bounds the reinforcing layer 36to the inner layer 34. The reinforcing layer 36 is comprised of aproximal reinforcing layer 40 which is formed from braided stainlesssteel wires and a distal reinforcing layer 42 which is formed from asingle helically wound platinum wire. The soft outer layer 38 is heatbonded onto the reinforcing layer 36. Accordingly, with the proximalsection of the catheter having the inner tubular member formed with abraided reinforcing layer, this section of the catheter becomesrelatively stiff and has a relatively high column strength so that thecatheter may be pushed into and through the vasculature of the humanbody. On the other hand, the distal section of the catheter is formedwith the inner tubular member comprised of a single helically wound wirewhich, while being sufficiently stiff to resist kinking, is still veryflexible and is capable of traversing tortuous vessels.

[0026] As may now be appreciated, with the balloon catheter asillustrated in FIG. 1, the proximal section of the catheter is formedwith an outer tubular member portion of an increased diameter and aninner tubular member which is formed by bonding a reinforcing layer ofwoven stainless steel wires between two polymer layers thereby providinga proximal catheter section which exhibits the characteristic of havingrelatively high column strength. The distal section of the catheter isformed with an outer tubular member having a reduced outer and innerdiameter and with a single helically wound wire bonded between twopolymer tubular members to thereby provide a distal section which isrelatively kink resistant, but still remains very flexible.

[0027]FIG. 2 more clearly shows the balloon catheter near the proximalportion of the inflatable balloon. A first layer of adhesive material 44is applied to a portion of the distal end 8 of the outer tubular member4 and the proximal portion 22 of the balloon 18 is fit over theadhesive-covered portion. A first retaining ring 46 is positioned overthe proximal portion 22 of the balloon 18 and is crimped onto theproximal end of the balloon, preferably using a crimping fixture. Thefirst retaining ring 46 acts to reinforce the adhesive bond between theouter tubular member 4 and the proximal portion 22 of the balloon 18. Aproximal marker band sleeve 48 is positioned over at least a half of theproximal end of the first retaining ring 46 and heat fused in place. Theproximal marker band sleeve 48 prevents longitudinal movement of thefirst retaining ring 46 during balloon inflation and helps to ensurethat the retaining ring does not become separated from the ballooncatheter in the event the balloon ruptures.

[0028] A purge aperture 50 extends through a wall of the outer tubularmember 4 at a point proximal to the proximal marker band sleeve 48. Thesequence for purging the balloon using the purge aperture 50 is depictedin FIGS. 4 through 7, which are discussed in detail below.

[0029]FIG. 3 more clearly shows the balloon catheter near the distalportion of the inflatable balloon. The distal portion 24 of the balloon18 is attached to the inner tubular member 10 by similar components usedto attach the proximal portion. The distal end 14 of the inner tubularmember 10 is inserted inside the distal portion 24 of the balloon. Asecond retaining ring 52 is positioned over the distal portion 24 of theballoon 18 and the distal end 14 of the inner tubular member 10. Asecond layer of adhesive material 54 is applied onto the distal end 14of the inner tubular member 10 and under the distal portion 24 of theballoon 18, such that the inner surface of the distal portion 24 of theballoon is in contact with the second layer of adhesive material 54. Thesecond retaining ring 52 is crimped onto the distal end of the balloon18, preferably using a crimping fixture, and excess balloon material istrimmed distal to the second retaining ring 52. The distal marker bandsleeve 56 is inserted over the distal end 14 of the inner tubular member10. The distal marker band sleeve 56 is heat fused to the inner tubularmember 10 distal to the second retaining ring 52.

[0030] When purging the balloon catheter of air, the inflatable balloon18 is placed within a protective tube 58, as shown in FIG. 4, torestrict the expansion of the balloon during purging. As can beappreciated, the protective tube 58 allows the balloon 18 to withstandthe fluid pressure exerted during purging. Preferably, this pressure isbetween about 20 psi and 45 psi, but may be as high as 90 psi. Withoutthe protective tube, the balloon would likely burst during inflation atthese pressures. The protective tube 58 is preferably formed of a rigidpolymer, but a metallic material could also be used. The inner diameterof the protective tube 58 should allow for some radial expansion of theinflatable balloon.

[0031] As shown in FIG. 5, the protective tube restricts the expansionof the balloon during purging and reduces the likelihood that theballoon will burst. Purging liquid is introduced through the lumen ofthe hub and into the inflation lumen of the catheter. As the liquidadvances through the catheter body, air is forced through the purgeaperture 50. Once the liquid reaches the purge aperture 50, the apertureis blocked and any air distal to the purge aperture is trapped withinthe inflatable balloon 18. Typically, a small drop of purge liquid formsat the location of the purge aperture to indicate that the catheter bodyhas been purged of air. Once the catheter body has been purged, theprotective tube 58 is removed, as shown in FIG. 6.

[0032]FIG. 7 shows the balloon after additional liquid has beenintroduced into the catheter body, thereby inflating the balloon. If airis observed within the balloon, the balloon is kept inflated to allowthe air to diffuse through the wall of the inflated balloon. Thisextended inflation period also allows the user to visually inspect theballoon to ensure that the balloon was not damaged by the higher liquidpressure exerted during purging. Once all of the air has been removedfrom the balloon, the balloon is submerged in liquid to prevent air fromre-entering the catheter while the balloon is deflated.

[0033] The first and second retaining rings, 46 and 52, respectively,are made of a radiopaque and biocompatible material, preferably gold,allowing for the precise positioning of the inflatable balloon as it isdeployed into the human body. The marker band sleeves provide supportfor the retaining rings and prevent them from moving along the length ofthe outer or inner tubular members, especially when the balloon isinflated. Additionally, the marker band sleeves help to ensure that theretaining rings do not become separated from the assembly in the eventthat the balloon ruptures.

[0034] In a preferred construction of the present invention, the outertubular member 4 is formed from polyurethane material and the inflatableballoon 18 is formed from a polyethylene elastomer or, preferably, asilicone material. The outside diameter of the proximal section of theouter tubular member 4 has an outside diameter of 0.043 inches and aninside diameter of 0.038 inches. The distal section of the outer tubularmember 4 has an outside diameter of 0.0365 inches and an inside diameterof 0.0315 inches. In addition, the thin inner layer 34 of the inner tubemember 10 is formed from PTFE material and has a thickness ofapproximately 0.0015 inches. The soft outer layer 38 of the innertubular member 10 is preferably formed of polyurethane material and hasa thickness of approximately 0.0025 inches.

[0035] The helical wound coil in the distal reinforcing layer 42 isformed of platinum wire having a circular cross section and with adiameter of approximately 0.0015 inches, and the braiding in theproximal reinforcing layer 40 is formed of stainless steel wire ofcircular cross-section. The wire forming the stainless steel braidpreferably has a diameter of about 0.0015 inches.

[0036] The layers of adhesive material are formed from siliconeapproximately 0.001 inches thick. The length of the first layer is 0.040inches and the length of the second layer is 0.023 inches. The firstretaining ring 46 has a nominal diameter of 0.0375 inches and decreasesby approximately 0.002 inches after being crimped. The first retainingring 46 is approximately 0.040 inches wide. The second retaining ring 52has a nominal diameter of 0.030 inches and decreases by approximately0.0025 inches after being crimped. The second retaining ring 52 isapproximately 0.023 inches wide.

[0037] The proximal marker band sleeve 48 is made from nylon materialwith an outer diameter of 0.0385 inches, an inner diameter of 0.036inches, and a length of 0.040 inches. The proximal marker band sleeve 48is positioned such that it overlaps at least half of the length of thefirst retaining ring 46. The distal marker band sleeve 56 is made frompolyurethane material with an outer diameter of 0.0315 inches, an innerdiameter of 0.0275 inches, and a length of 0.030 inches. The materialsfor the marker band sleeves were chosen relative to the durometers ofthe outer and inner tubular members that the marker band sleeves areattached to. The inner tubular member is more flexible than the outertubular member is, so a more flexible material was chosen for the distalmarker band sleeve.

[0038] The purge aperture 50 is preferably circular with a diameterbetween about 0.0005 and 0.0014 inches, with a diameter of about 0.0010inches being preferred. The purge aperture is preferably formed using aheated wire, although other methods know to the art could be used aswell. As can be appreciated, the purge aperture could take other shapes,such as an ellipse or rectangle. Multiple purge apertures of smallerdimension could also be employed.

[0039] The purge aperture 50 is located as close to the first retainingring 46 as possible to allow as much air as possible to be purged fromthe catheter body. Typically, this distance is about 0.020 inchesproximal to the first retaining ring. As can be appreciated, alternatemethods of attaching the gas-permeable balloon to the catheter may beemployed. In such cases, the purge aperture should be located as closeto the proximal balloon-catheter junction as possible.

[0040] As can be appreciated, the purge mechanism of the presentinvention is applicable to other catheter configurations. For example, asingle-lumen catheter could be used in place of the dual-lumen catheterdescribed above. In such a case, the proximal and distal portions of theballoon would be attached to the same catheter body. Likewise, amulti-lumen configuration is also possible.

[0041] As is apparent, there are numerous modifications of the preferredembodiment described above that will be readily apparent to one skilledin the art to which this invention relates. These modifications areintended to be within the scope of the claims that follow.

That which is claimed is:
 1. A balloon catheter comprising: a catheterbody comprising at least one tubular member having a tubular wall andhaving a lumen extending throughout the length of the tubular member,said tubular member further having a proximal end and a distal end; aninflatable balloon having a main body portion, a proximal portion, and adistal portion, said proximal portion and said distal portion extendingfrom said main body portion, said distal portion of the balloon beingbonded to the tubular member near the distal end of the tubular memberand said proximal portion of the balloon being bonded to the tubularmember proximal to the distal portion of the balloon, said inflatableballoon being formed from a gas-permeable material; a coupling memberhaving a lumen extending therethrough, said coupling member beingmounted on the proximal end of the tubular member and the lumen of thecoupling member communicating with the lumen of the tubular member; asyringe coupled to said coupling member for applying a liquid within thelumen of the tubular member; and, at least one aperture for purging airfrom said lumen of the catheter body, said aperture extending radiallythrough said wall of the tubular member at a point proximal to theproximal portion of the inflatable balloon.
 2. A balloon catheter asdefined in claim 1, wherein said aperture is circular and has a diameterbetween approximately 0.0005 inches and 0.0014 inches.
 3. A ballooncatheter as defined in claim 2, wherein said aperture is circular andhas a diameter of approximately 0.0010 inches.
 4. A balloon catheter asdefined in claim 2, wherein said liquid applied within the lumen of thetubular member exerts a fluid pressure between about 20 psi and 45 psiand thereby causes air to pass through the aperture.
 5. A ballooncatheter as defined in claim 4, wherein said inflatable balloon isplaced within a protective tube thereby restricting the ability of theballoon to inflate.
 6. A balloon catheter comprising: a catheter bodyincluding an outer tubular member having a tubular wall and having alumen extending throughout the length of the outer tubular member, saidouter tubular member further having a proximal end and a distal end;said catheter body further including an inner tubular member having aproximal end, a distal end, and a lumen extending therethrough, saidinner tubular member being disposed coaxially through said lumen of theouter tubular member; an inflatable balloon having a main body portion,a proximal portion, and a distal portion, said proximal portion and saiddistal portion extending from said main body portion, said proximalportion of the balloon being bonded to the distal end of the outertubular member and the distal portion of the balloon being bonded to thedistal end of the inner tubular member, said inflatable balloon beingformed from a gas-permeable material; a coupling member having a lumenextending therethrough, said coupling member being mounted on theproximal end of the outer tubular member and the lumen of the couplingmember communicating with the lumen between the outer tubular member andthe inner tubular member; a syringe coupled to said coupling member forapplying a liquid within the lumen of the outer tubular member; and, atleast one aperture for purging air from said lumen of the catheter body,said aperture extending radially through said wall of the outer tubularmember at a point proximal to the proximal end of the inflatableballoon.
 7. A balloon catheter as defined in claim 6, wherein saidaperture is circular and has a diameter between approximately 0.0005inches and 0.0014 inches.
 8. A balloon catheter as defined in claim 7,wherein said aperture is circular and has a diameter of approximately0.0010 inches.
 9. A balloon catheter as defined in claim 7, wherein saidliquid applied within the lumen of the outer tubular member exerts afluid pressure between about 20 psi and 45 psi and thereby causes air topass through the aperture.
 10. A balloon catheter as defined in claim 9,wherein said inflatable balloon is placed within a protective tubethereby restricting the ability of the balloon to inflate.
 11. A ballooncatheter comprising: a catheter body comprising at least one tubularmember having a tubular wall and having a lumen extending throughout thelength of the tubular member, said tubular member further having aproximal end and a distal end; an inflatable balloon having a main bodyportion, a proximal portion, and a distal portion, said proximal portionand said distal portion extending from said main body portion, saiddistal portion of the balloon being bonded to the tubular member nearthe distal end of the tubular member and said proximal portion of theballoon being bonded to the tubular member proximal to the distalportion of the balloon; a coupling member having a lumen extendingtherethrough, said coupling member being mounted on the proximal end ofthe tubular member and the lumen of the coupling member communicatingwith the lumen of the tubular member such that a liquid may be appliedwithin the lumen of the tubular member; and, at least one aperture forpurging air from said lumen of the catheter body, said apertureextending radially through said wall of the tubular member at a pointproximal to the proximal portion of the inflatable balloon.
 12. Aballoon catheter as defined in claim 11, wherein said aperture iscircular and has a diameter between approximately 0.0005 inches and0.0014 inches.
 13. A balloon catheter as defined in claim 12, whereinsaid aperture is circular and has a diameter of approximately 0.0010inches.
 14. A balloon catheter as defined in claim 12, wherein saidliquid applied within the lumen of the tubular member exerts a fluidpressure between about 20 psi and 45 psi and thereby causes air to passthrough the aperture.
 15. A balloon catheter as defined in claim 14,wherein said inflatable balloon is placed within a protective tubethereby restricting the ability of the balloon to inflate.
 16. A ballooncatheter as defined in claim 15, wherein said inflatable balloon isformed of a gas-permeable material.
 17. A method of purging air from aballoon catheter which includes a tubular member having a tubular walland proximal and distal ends; an inflatable balloon having a main bodyportion and proximal and distal portions extending from said main bodyportion, said proximal and distal portions each being attached to thetubular member; a syringe coupled to the tubular member for applying aliquid within a lumen of the tubular member, a purge aperture extendingthrough the wall of the tubular member at a point proximal to theproximal portion of the inflatable balloon; wherein the method includesthe steps of: placing the inflatable balloon within a protective tube torestrict the inflation of the balloon; injecting liquid into the lumenof the tubular member thereby forcing air to be evacuated from theballoon catheter through the purge aperture; removing the protectivetube; inflating the balloon; allowing any air remaining within theballoon to diffuse through the inflated balloon; and, submerging theballoon in liquid while deflating the balloon to prevent air fromre-entering the tubular member.